Thin and dry diaper

ABSTRACT

An absorbent article, preferably a disposable absorbent article such as a diaper, is disclosed having an absorbent core which imparts increased wearing comfort to the article and makes it thin and dry. The absorbent core useful for an absorbent article comprises a substrate layer, a discontinuous layer of absorbent material, and a layer of thermoplastic material. A second surface of the discontinuous layer of absorbent material is in at least partial contact with a first surface of the substrate layer. Portions of a second surface of the layer of thermoplastic material are in direct contact with the first surface of the substrate layer and portions of said second surface of the layer of thermoplastic material are in direct contact with a first surface of the discontinuous layer of absorbent material. A process for providing a storage layer for an absorbent core useful in an absorbent article is further disclosed.

FIELD OF THE INVENTION

[0001] The present invention concerns an absorbent article, preferably adisposable absorbent article, such as a diaper. The present inventionspecifically concerns an absorbent core for such an absorbent articlethat provides an improved immobilization of absorbent polymer materialwhen the article is fully or partially urine loaded. This absorbent coreis useful for providing an absorbent article of increased wearingcomfort, which is thin and dry.

BACKGROUND

[0002] Absorbent articles, such as diapers and adult incontinenceproducts are well known articles of staple manufacturing. Multipleattempts have been made to provide them with an overall good fit andwith a high absorbent capacity. Modem diapers make use of absorbentpolymer materials or so-called superabsorbent materials, which allow forstorage of amounts of liquid as high as 300 ml of in a typical babydiaper.

[0003] While such a diaper is generally a disposable product it is insome instances worn over many hours and worn in a dry state as well asin a urine loaded state.

[0004] Hence, to provide good wearing comfort it is very important tokeep the absorbent materials of a diaper or other absorbent article intheir intended position, both when the article is dry and when thearticle is fully or partially loaded with urine (or other bodilyliquids).

[0005] U.S. Pat. No. 4,381,783 (Elias) discloses an absorbent articlewith a core comprising pockets of absorbent hydrocolloid material. Thesepockets are provided as to confine the movement of the hydrocolloidmaterial, in particular when the article is fully or partially loadedwith urine. The pockets form part of an absorbent layer and aretypically provided from cellulose material. Hence, to achieve goodimmobilization of the hydrocolloid material according to the teaching ofthis patent, a relatively high amount of cellulosic material isrequired. Moreover, the provision of such pockets may hinder the freedistribution of liquid to the more absorbent areas of the core, forexample the areas of hydrocolloid materials.

[0006] U.S. Pat. No. 5,944,706 (Palumbo) discloses an absorbentstructure comprising two fibre layers and an intermediate layer. Thisintermediate layer comprises an absorbent hydrogel material in an amountexceeding 120 g/m² and particles of an thermoplastic material. Whilethis construction certainly provides good immobilisation of theabsorbent hydrogel particles in the dry state, it seems that only alesser immobilisation can be achieved in the urine loaded state. Thedisclosed thermoplastic materials appear to swell much less than thedisclosed hydrogel materials. Therefore, in particular when theabsorbent structure is to be used in a product to absorb high amounts ofliquids, for example a diaper, the wet immobilisation may not be fullysatisfactory.

[0007] U.S. Pat. No. 5,411,497 (Tanzer) discloses an absorbent articlewhich includes superabsorbent material located in discrete pockets. Theabsorbent article comprises a first and a second carrier layer andwater-sensitive attaching means for securing together the carrier layersand to provide a plurality of pocket regions. The article compriseshigh-absorbency material located within said pocket regions. Thewater-sensitive attachment means provides a wet strength which is lessthan a separating force imparted by a swelling of that high-absorbencymaterial when that high-absorbency material is exposed to an aqueousliquid. The absorbent article is said to provide an absorbent structurewhich more securely locates and contains the high-absorbency material ina selected way of pockets when the article is dry. However, due to theconstruction of the pockets, and specifically due to the selection ofthe water-sensitive attachment means, these pockets are not maintainedwhen the article is fully or partially loaded with liquids. Therefore,it is believed that this absorbent article does not provide a verysatisfactory immobilization of the absorbent material in the fully orpartially urine loaded state.

SUMMARY

[0008] The present invention concerns an absorbent article, preferably adisposable absorbent article, such as a diaper. An absorbent core usefulfor an absorbent article is disclosed which imparts increased wearingcomfort to the article and makes it thin and dry. Further disclosed is aprocess for obtaining such a core. Specifically disclosed is anabsorbent core useful for an absorbent article comprising a substratelayer, the substrate layer comprising a first surface and a secondsurface, the absorbent core further comprising a discontinuous layer ofabsorbent material, the absorbent material comprising an absorbentpolymer material, the absorbent material optionally comprising anabsorbent fibrous material and the absorbent fibrous material notrepresenting more than 20 weight percent of the total weight of theabsorbent polymer material, the discontinuous layer of absorbentmaterial comprising a first surface and a second surface, the absorbentcore further comprising a layer of thermoplastic material, the layer ofthermoplastic material comprising a first surface and a second surfaceand wherein the second surface of the discontinuous layer of absorbentmaterial is in at least partial contact with the first surface of thesubject layer and wherein portions of the second surface of the layer ofthermoplastic material are in direct contact with the first surface ofthe substrate layer and portions of the second surface of the layer ofthermoplastic material are in direct contact with the first surface ofthe discontinuous layer of absorbent material.

[0009] Further disclosed is a process for providing a storage layer foran absorbent core useful in an absorbent article, the process comprisingthe steps of:

[0010] providing a substrate material comprising a first surface and asecond surface

[0011] depositing absorbent material onto the first surface of thesubstrate material in a pattern, the pattern comprising at least onezone which is substantially free of absorbent material, and the patterncomprising at least one zone comprising absorbent material

[0012] depositing a thermoplastic material onto the first surface of thesubstrate material and the absorbent material, such that portioris ofthe thermoplastic material are in direct contact with the first surfaceof the substrate and portions of the thermoplastic material are indirect contact with the absorbent material.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013]FIG. 1 is a plan view of a diaper as a preferred embodiment of anabsorbent article according to the present invention.

[0014]FIG. 2 is a cross-sectional view of the diaper shown in FIG. 1taken along the sectional line 2-2 of FIG. 1.

[0015]FIG. 3 is a cross-sectional view of a preferred embodiment of theabsorbent core.

[0016]FIG. 4 is a cross-sectional view of a preferred embodiment of theabsorbent core.

[0017]FIG. 5 is a perspective view of a preferred embodiment of theabsorbent core.

[0018]FIG. 6 is a cross-sectional view of a preferred embodiment of theabsorbent core.

[0019]FIG. 7 is a schematic representation of the rheometer

DETAILED DESCRIPTION

[0020] The present invention concerns an absorbent article, preferably adisposable absorbent article, such as a diaper.

[0021] As used herein, the following terms have the following meanings:

[0022] “Absorbent article” refers to devices that absorb and containliquid, and more specifically, refers to devices that are placed againstor in proximity to the body of the wearer to absorb and contain thevarious exudates discharged from the body. Absorbent articles includebut are not limited to diapers, adult incontinence briefs, trainingpants, diaper holders and liners, sanitary napkins and the like.

[0023] “Disposable” is used herein to describe articles that aregenerally not intended to be laundered or otherwise restored or reused(i.e., they are intended to be discarded after a single use and,preferably, to be recycled, composted or otherwise disposed of in anenvironmentally compatible manner).

[0024] “Diaper” refers to an absorbent article generally worn by infantsand incontinent persons about the lower torso.

[0025] “Comprise,” “comprising,” and “comprises” is an open ended termthat specifies the presence of what follows, e.g., a component but doesnot preclude the presents of other features, elements, steps orcomponents known in the art, or disclosed herein.

[0026]FIG. 1 is a plan view of a diaper 20 as a preferred embodiment ofan absorbent article according to the present invention. The diaper isshown in its flat out, uncontracted state (i.e., without elastic inducedcontraction). Portions of the structure are cut away to more clearlyshow the underlying structure of the diaper 20. The portion of thediaper 20 that contacts a wearer is facing the viewer. The chassis 22 ofthe diaper 20 in FIG. 1 comprises the main body of the diaper 20. Thechassis 22 comprises an outer covering including a liquid pervioustopsheet 24 and/or a liquid impervious backsheet 26. The chassis mayinclude a portion of an absorbent core 28 encased between the topsheet24 and the backsheet 26. The chassis may also include most or all of theabsorbent core 28 encased between the topsheet 24 and the backsheet 26.The chassis preferably further includes side panels 30, elasticized legcuffs 32, and elastic waist feature 34, the leg cuffs 32 and the elasticwaist feature each typically comprise elastic members 33. One endportion of the diaper 20 is configured as a first waist region 36 of thediaper 20. The opposite end portion is configured as a second waistregion 38 of the diaper 20. An intermediate portion of the diaper 20 isconfigured as a crotch region 37, which extends longitudinally betweenthe first and second waist regions 36 and 38. The waist regions 36 and38 may include elastic elements such that they gather about the waist ofthe wearer to provide improved fit and containment (elastic waistfeature 34). The crotch region 37 is that portion of the diaper 20which, when the diaper 20 is worn, is generally positioned between thewearer's legs. The diaper 20 is depicted with its longitudinal axis 10and its transverse axis 12. The periphery of the diaper 20 is defined bythe outer edges of the diaper 20 in which the longitudinal edges 44 rungenerally parallel to the longitudinal axis 100 of the diaper 20 and theend edges 46 run between the longitudinal edges 44 generally parallel tothe transverse axis 110 of the diaper 20. The chassis also comprises afastening system, which may include at least one fastening member 40 andat least one stored landing zone 42.

[0027] For unitary absorbent articles, the chassis 22 comprises the mainstructure of the diaper with other features added to form the compositediaper structure. While the topsheet 24, the backsheet 26, and theabsorbent core 28 may be assembled in a variety of well-knownconfigurations, preferred diaper configurations are described generallyin U.S. Pat. No. 5,554,145 entitled “Absorbent Article With MultipleZone Structural Elastic-Like Film Web Extensible Waist Feature” issuedto Roe et al. on Sep. 10, 1996; U.S. Pat. No. 5,569,234 entitled“Disposable Pull-On Pant” issued to Buell et al. on Oct. 29, 1996; andU.S. Pat. No. 6,004,306 entitled “Absorbent Article WithMulti-Directional Extensible Side Panels” issued to Robles et al. onDec. 21, 1999.

[0028] The topsheet 24 in FIG. 1 may be fully or partially elasticizedor may be foreshortened to provide a void space between the topsheet 24and the absorbent core 28. Exemplary structures including elasticized orforeshortened topsheets are described in more detail in U.S. Pat. No.5,037,416 entitled “Disposable Absorbent Article Having ElasticallyExtensible Topsheet” issued to Allen et al. on Aug. 6, 1991; and U.S.Pat. No. 5,269,775 entitled “Trisection Topsheets for DisposableAbsorbent Articles and Disposable Absorbent Articles Having SuchTrisection Topsheets” issued to Freeland et al. on Dec. 14, 1993.

[0029] The absorbent core 28 in FIG. 1 generally is disposed between thetopsheet 24 and the backsheet 26. The absorbent core 28 may comprise anyabsorbent material that is generally compressible, conformable,non-irritating to the wearer's skin, and capable of absorbing andretaining liquids such as urine and other certain body exudates. Theabsorbent core 28 may comprise a wide variety of liquid-absorbentmaterials commonly used in disposable diapers and other absorbentarticles such as comminuted wood pulp, which is generally referred to asair felt. Examples of other suitable absorbent materials include crepedcellulose wadding; melt blown polymers, including co-form; chemicallystiffened, modified or cross-linked cellulosic fibers; tissue, includingtissue wraps and tissue laminates; absorbent foams; absorbent sponges;superabsorbent polymers; absorbent gelling materials; or any other knownabsorbent material or combinations of materials. The absorbent core 28may further comprise minor amounts (typically less than 10%) ofnon-liquid absorbent materials, such as adhesives, waxes, oils and thelike.

[0030] Exemplary absorbent structures for use as the absorbentassemblies are described in U.S. Pat. No. 4,610,678 (Weisman et al.);U.S. Pat. 4,834,735 (Alemany et al.); U.S. Pat. 4,888,231 (Angstadt);U.S. Pat. No. 5,260,345 (DesMarais et al.); U.S. Pat. No. 5,387,207(Dyer et al.); U.S. Pat. No. 5,397,316 (LaVon et al.); and U.S. Pat. No.5,625,222 (DesMarais et al.).

[0031] The backsheet 26 may be joined with the topsheet 24. Thebacksheet 26 prevents the exudates absorbed by the absorbent core 28 andcontained within the article 20 from soiling other external articlesthat may contact the diaper 20, such as bed sheets and undergarments. Inpreferred embodiments, the backsheet 26 is substantially impervious toliquids (e.g., urine) and comprises a laminate of a nonwoven and a thinplastic film such as a thermoplastic film having a thickness of about0.012 mm (0.5 mil) to about 0.051 mm (2.0 mils). Suitable backsheetfilms include those manufactured by Tredegar Industries Inc. of TerreHaute, Ind. and sold under the trade names X15306, X10962, and X10964.Other suitable backsheet materials may include breathable materials thatpermit vapors to escape from the diaper 20 while still preventingexudates from passing through the backsheet 26. Exemplary breathablematerials may include materials such as woven webs, nonwoven webs,composite materials such as film-coated nonwoven webs, and microporousfilms such as manufactured by Mitsui Toatsu Co., of Japan under thedesignation ESPOIR NO and by EXXON Chemical Co., of Bay City, Tex.,under the designation EXXAIRE. Suitable breathable composite materialscomprising polymer blends are available from Clopay Corporation,Cincinnati, Ohio under the name HYTREL blend P18-3097. Such breathablecomposite materials are described in greater detail in PCT ApplicationNo. WO 95/16746, published on Jun. 22, 1995 in the name of E. I. DuPont.Other breathable backsheets including nonwoven webs and apertured formedfilms are described in U.S. Pat. No. 5,571,096 issued to Dobrin et al.on Nov. 5, 1996.

[0032] The diaper 20 may also include such other features as are knownin the art including front and rear ear panels, waist cap features,elastics and the like to provide better fit, containment and aestheticcharacteristics. Such additional features are well known in the art andare e.g., described in U.S. Pat. No. 3,860,003 and U.S. Pat. No.5,151,092.

[0033] In order to keep the diaper 20 in place about the wearer,preferably at least a portion of the first waist region 36 is attachedby the fastening member 42 to at least a portion of the second waistregion 38, preferably to form leg opening(s) and an article waist. Whenfastened, the fastening system carries a tensile load around the articlewaist. The fastening system is designed to allow an article user to holdone element of the fastening system such as the fastening member 42, andconnect the first waist region 36 to the second waist region 38 in atleast two places. This is achieved through manipulation of bondstrengths between the fastening device elements.

[0034] Diapers 20 according to the present invention may be providedwith a re-closable fastening system or may alternatively provided in theform of pant-type diapers.

[0035] The fastening system and any component thereof may include anymaterial suitable for such a use, including but not limited to plastics,films, foams, nonwoven webs, woven webs, paper, laminates, fiberreinforced plastics and the like, or combinations thereof. It may bepreferable that the materials making up the fastening device beflexible. The flexibility is designed to allow the fastening system toconform to the shape of the body and thus, reduces the likelihood thatthe fastening system will irritate or injure the wearer's skin.

[0036]FIG. 2 shows a cross section of FIG. 1 taken along the sectionalline 2-2 of FIG. 1. Starting from the wearer facing side the diapercomprises the topsheet 24, the components of the absorbent core 28, andthe backsheet 26. The absorbent article preferably comprises anacquisition system 50, which comprises an upper acquisition layer 52facing towards the wearer's skin and a lower acquisition 54 layer facingthe garment of the wearer. In one preferred embodiment the upperacquisition layer 52 comprises a non-woven whereas the lower acquisitionlayer preferably comprises a mixture of chemically stiffened, twistedand curled fibers, high surface area fibers and thermoplastic bindingfibers. In another preferred embodiment both acquisition layers areprovided from a non-woven material, which is preferably hydrophilic. Theacquisition layer preferably may be in direct contact with the storagelayer 60.

[0037] The storage layer 60 may be wrapped by a core wrap material. Inone preferred embodiment the core wrap material comprises a top layer 56and a bottom layer 58. The core wrap material, the top layer 56 or thebottom layer 58 can be provided from a non-woven material. One preferredmaterial is a so called SMS material, comprising a spunbonded, amelt-blown and a further spunbonded layer. Highly preferred arepermanently hydrophilic non-wovens, and in particular nonwovens withdurably hydrophilic coatings. An alternative preferred materialcomprises a SMMS-structure.

[0038] The top layer 56 and the bottom layer 58 may be provided from twoor more separate sheets of materials or they may be alternativelyprovided from a unitary sheet of material. Such a unitary sheet ofmaterial may be wrapped around the storage layer 60 e.g., in a C-fold.

[0039] Preferred non-woven materials are provided from synthetic fibers,such as PE, PET and most preferably PP. As the polymers used fornonwoven production are inherently hydrophobic, they are preferablycoated with hydrophilic coatings.

[0040] A preferred way to produce nonwovens with durably hydrophiliccoatings, is via applying a hydrophilic monomer and a radicalpolymerization initiator onto the nonwoven, and conducting apolymerization activated via UV light resulting in monomer chemicallybound to the surface of the nonwoven as described in co-pending U.S.patent application Ser. No. 10/674,670.

[0041] An alternative preferred way to produce nonwovens with durablyhydrophilic coatings is to coat the nonwoven with hydrophilicnanoparticles as described in co-pending application Ser. No. 10/060,708and WO 02/064877.

[0042] Typically, nanoparticles have a largest dimension of below 750nm. Nanoparticles with sizes ranging form 2 to 750 nm can beeconomically produced. The advantages of nanoparticles is that many ofthem can be easily dispersed in water solution to enable coatingapplication onto the nonwoven; they typically form transparent coatings,and the coatings applied from water solutions are typically sufficientlydurable to exposure to water.

[0043] Nanoparticles can be organic or inorganic, synthetic or natural.Inorganic nanoparticles generally exist as oxides, silicates,carbonates. Typical examples of suitable nanoparticles are layered clayminerals (e.g., LAPONITE™ from Southern Clay Products, Inc. (USA), andBoehmite alumina (e.g., Disperal P2™ from North American Sasol. Inc.)

[0044] A highly preferred nanoparticle coated non-woven is disclosed inthe co-pending patent application Ser. No. 10/1758,066 entitled“Disposable absorbent article comprising a durable hydrophilic corewrap” to the inventors Ekaterina Anatolyevna Ponomarenko and Mattias NMNSchmidt.

[0045] Further useful non-wovens are described in U.S. Pat. No 6,645,569to Cramer et al. and co-pending patent applications Ser. No. 10/060,694to Cramer et al., 10/060,708 to Rohrbaugh et al., 10/338,603 to Crameret al., and 10/338,610 to Cramer et al.

[0046] In some cases, the nonwoven surface can be pre-treated with highenergy treatment (corona, plasma) prior to application of nanoparticlecoatings. High energy pre-treatment typically temporarily increases thesurface energy of a low surface energy surface (such as PP) and thusenables better wetting of a nonwoven by the nanoparticle dispersion inwater.

[0047] Notably, permanently hydrophilic non-wovens are also useful inother parts of an absorbent article. For example, topsheets andacquisition layers comprising permanently hydrophilic non-wovens asdescribed above have been found to work well.

[0048] In summary, in one aspect of the present invention, absorbentarticles are preferred which comprise a nonwoven fabric, the nonwovenfabric comprising a plurality of fibers and having a surface tension ofat least 55, preferably at least 60 and most preferably at least 65 mN/mor higher when being wetted with saline solution and has a liquid strikethrough time of less than 5 s for a fifth gush of liquid.

[0049] The surface tension is a measure of how permanently a certainhydrophilicity level is achieved. The value is to be measured using thetest method described hereinbelow.

[0050] The liquid strike through time is a measure of a certainhydrophilicity level. The value is to be measured using the test methoddescribed hereinbelow.

[0051] In a preferred embodiment of the present invention the absorbentcore 28 comprises a substrate layer 100, absorbent polymer material 110and a fibrous layer of adhesive 120. The substrate layer 100 ispreferably provided from a non-woven material, preferred non-wovens arethose exemplified above for the top layer 56 or the bottom layer 58.

[0052] The substrate layer 100 comprises a first surface and a secondsurface. At least portions of the first surface of the substrate layer100 are in direct contact with a layer of absorbent polymer material110. This layer of absorbent polymer material 110 is preferably adiscontinuous layer, and comprises a first surface and a second surface.As used herein, a discontinuous layer is a layer comprising openings.Typically these openings have a diameter or largest span of less than 10mm, preferably less than 5 mm, 3 mm, 2 mm and of more than 0.5 mm, 1 mmor 1.5 mm. At least portions of the second surface of the absorbentpolymer material layer 110 are in contact with at least portions of thefirst surface of the substrate layer material 100. The first surface ofthe absorbent polymer material 110 defines a certain height 112 of thelayer of absorbent polymer above the first surface of the layer ofsubstrate material 100. When the absorbent polymer material layer 110 isprovided as a discontinuous layer, portions of the first surface of thesubstrate layer 100 are not covered by absorbent polymer material 110.The absorbent core 28 further comprises a thermoplastic composition 120.This thermoplastic composition 120 serves to at least partiallyimmobilize the absorbent polymer material 110.

[0053] However, in an even more preferred embodiment of the presentinvention the thermoplastic material 120 is provided as a fibrous layerwhich is partially in contact with the absorbent polymer material 110and partially in contact with the substrate layer 100. FIG. 3 shows sucha preferred structure. In this preferred structure the absorbent polymermaterial layer 110 is provided as a discontinuous layer, a layer offibrous thermoplastic material 120 is laid down onto the layer ofabsorbent polymeric material 110, such that the thermoplastic layer 120is in direct contact with the first surface of the layer of absorbentpolymer material 110, but also in direct contact with the first surfaceof the substrate layer 100, where the substrate layer is not covered bythe absorbent polymeric material 110. This imparts an essentiallythree-dimensional structure to the fibrous layer of thermoplasticmaterial 120 which in itself is essentially a two-dimensional structureof relatively small thickness (in z-direction), as compared to theextension in x- and y-direction. In other words, the fibrousthermoplastic material layer 120 undulates between the first surface ofthe absorbent polymer material 110 and the first surface of thesubstrate layer 100.

[0054] Thereby, the thermoplastic material 120 provides cavities to holdthe absorbent polymer material 110, and thereby immobilizes thismaterial. In a further aspect, the thermoplastic material 120 bonds tothe substrate 100 and thus affixes the absorbent polymer material 110 tothe substrate 100. Highly preferred thermoplastic materials will alsopenetrate into both the absorbent polymer material 110 and the substratelayer 100, thus providing for further immobilization and affixation.

[0055] Of course, while the thermoplastic materials disclosed hereinprovide a much improved wet immobilisation (i.e., immobilisation ofabsorbent material when the article is wet or at least partiallyloaded), these thermoplastic materials also provide a very goodimmobilisation of absorbent material when the article is dry.

[0056] In accordance with the present invention, the absorbent polymermaterial 110 may also be mixed with fibrous material, such as airfeltmaterial, which can provide a matrix for further immobilization of thesuper-absorbent polymer material. However, preferably a relatively lowamount of fibrous cellulose material is used, preferably less than 40weight %, 20 or 10 weight % of cellulose fibrous material as compared tothe weight of absorbent polymer material 110.

[0057] An alternative preferred embodiment of the present invention isshown in FIG. 4. The absorbent core shown in FIG. 4 further comprises acover layer 130. This cover layer may be provided of the same materialas the substrate layer 100, or may be provided from a differentmaterial. Preferred materials for the cover layer are the non-wovenmaterials, typically the materials described above as useful for the toplayer 56 and the bottom layer 58. In this embodiment portions of thecover layer 130 bond to portions of the substrate layer 100 via thethermoplastic material 120. Thereby, the substrate layer 100 togetherwith the cover layer 130 provides cavities to immobilize the absorbentpolymer material 110.

[0058] With reference to FIGS. 3 and 4 the areas of direct contactbetween the thermoplastic material 120 and the substrate material 100are referred to as areas of junction 140. The shape number anddisposition of the areas of junction 140 will influence theimmobilization of the absorbent polymer material 110. The areas ofjunction can be of squared, rectangular or circular shape. Preferredareas of junction are of circular shape. Preferably, they have adiameter of more than 0.5 mm, or 1 mm, or 1.5 mm and of less than 10 mm,or 5 mm, or 3 mm, or 2 mm. If the areas of junction 140 are not ofcircular shape, they preferably are of a size as to fit inside a circleof any of the preferred diameters given above.

[0059] The areas of junction 140 can be disposed in a regular orirregular pattern. For example, the areas of junction 140 may bedisposed along lines as shown in FIG. 5. These lines may be aligned withthe longitudinal axis of the absorbent core, or alternatively they mayhave a certain angle in respect to the longitudinal edges of the core.It has been found, that a disposition along lines parallel with thelongitudinal edges of the absorbent core 28 create channels in thelongitudinal direction which lead to a lesser wet immobilization.Preferably, therefore the areas of junction 140 are arranged along lineswhich form an angle of 20 degree, 30 degree, 40 degree, or 45 degreewith the longitudinal edges of the absorbent core 28. Another preferredpattern for the areas of junction 140 is a pattern comprising polygons,for example pentagons and hexagons or a combination of pentagons andhexagons. Also preferred are irregular patterns of areas of junction140, which also have been found to give a good wet immobilization.

[0060] Two fundamentally different patterns of areas of junctions 140can be chosen in accordance with the present invention. In oneembodiment the areas of junctions are discrete. They are positionedwithin the areas of absorbent material, like islands in a sea. The areasof absorbent materials are then referred to as connected areas. In analternative embodiment, the areas of junctions can be connected. Then,the absorbent material can be deposited in a discrete pattern, or inother words the absorbent material represents islands in a sea ofthermoplastic material 120. Hence, a discontinuous layer of absorbentpolymer material 110 may comprise connected areas of absorbent polymermaterial 110 or may comprise discrete areas of absorbent polymermaterial 110.

[0061] In a further aspect of the present invention, it has been foundthat absorbent cores providing for a good wet immobilization can beformed by combining two layers as shown in FIG. 3 and as described inthe context thereof. Such an embodiment is shown in FIG. 6. Theabsorbent core material shown in FIG. 6 comprises two substrate layers100, two layers of absorbent polymer material 110 and two layers offibrous thermoplastic materials 120. When two discontinuous layers of anabsorbent polymer material 110 are used, they would be typicallyarranged in such a way that the absorbent polymer material of the onelayer faces the areas of junction 140 of the other layer. In analternative preferred embodiment, however, the areas of junction 140 areoffset and do not face each other. Hence preferably, when two storagelayers are joined, this is done such that the first surface of thesubstrate layer 100 of the first storage layer 60 faces the firstsurface of the substrate layer 100 of the second storage layer 60.

[0062] The present invention, and specifically the preferred embodimentdescribed with reference to FIGS. 3, 4 and 6 can be used to provide thestorage layer 60 of an absorbent core. However, they can also be used toprovide the full absorbent core 28. In that case, no further materialswrapping the core, such as the top layer 56 and the bottom layer 58 arebeing used. With reference to the embodiment of FIG. 3 the substratelayer 100 may provide the function of the bottom layer 58 and the layerof fibrous thermoplastic material 120 may provide the function of thetop layer 56. With reference to FIG. 4 the cover layer 130 may providethe function of the top layer 56 and the substrate layer 100 may providethe function of the bottom layer 58. With reference to FIG. 6, the twosubstrate layers 100 used may provide the functions of the top layer 56and the bottom layer 58, respectively.

[0063] According to the present invention the thermoplastic layer 120can comprise any thermoplastic composition, preferred are adhesivethermoplastic compositions, also referred to as hot melt adhesives. Avariety of thermoplastic compositions are suitable to immobilizeabsorbent material.

[0064] Some initially thermoplastic materials may later lose theirthermoplasticity due to a curing step, e.g., initiated via heat, UVradiation, electron beam exposure or moisture or other means of curing,leading to the irreversible formation of a crosslinked network ofcovalent bonds. Those materials having lost their initial thermoplasticbehaviour are herein also understood as thermoplastic materials 120.

[0065] Without wishing to be bound by theory it has been found thatthose thermoplastic compositions are most useful for immobilizing theabsorbent polymer material 110, which combines good cohesion and goodadhesion behaviour. Good adhesion is critical to ensure that thethermoplastic layer 120 maintains good contact with the absorbentpolymer material 110 and in particular with the substrate 100. Goodadhesion is a challenge, namely when a non-woven substrate is used. Goodcohesion ensures that the adhesive does not break, in particular inresponse to external forces, and namely in response to strain. Theadhesive is subject to external forces when the absorbent product hasacquired liquid, which is then stored in the absorbent polymer material110 which in response swells. A preferred adhesive will allow for suchswelling, without breaking and without imparting too many compressiveforces, which would restrain the absorbent polymer material 110 fromswelling. Importantly, in accordance with the present invention theadhesive should not break, which would deteriorate the wetimmobilization. Preferred thermoplastic compositions meeting theserequirements have the following features:

[0066] The thermoplastic composition may comprise, in its entirety, asingle thermoplastic polymer or a blend of thermoplastic polymers,having a softening point, as determined by the ASTM Method D-36-95 “Ringand Ball”, in the range between 50° C. and 300° C., or alternatively thethermoplastic composition may be a hot melt adhesive comprising at leastone thermoplastic polymer in combination with other thermoplasticdiluents such as tackifying resins, plasticizers and additives such asantioxidants.

[0067] The thermoplastic polymer has typically a molecular weight (Mw)of more than 10,000 and a glass transition temperature (Tg) usuallybelow room temperature. Typical concentrations of the polymer in a hotmelt are in the range of 20-40% by weight. A wide variety ofthermoplastic polymers are suitable for use in the present invention.Such thermoplastic polymers are preferably water insensitive. Exemplarypolymers are (styrenic) block copolymers including A-B-A triblockstructures, A-B diblock structures and (A-B)n radial block copolymerstructures wherein the A blocks are non-elastomeric polymer blocks,typically comprising polystyrene, and the B blocks are unsaturatedconjugated diene or (partly) hydrogenated versions of such. The B blockis typically isoprene, butadiene, ethylene/butylene (hydrogenatedbutadiene), ethylene/propylene (hydrogenated isoprene), and mixturesthereof.

[0068] Other suitable thermoplastic polymers that may be employed aremetallocene polyolefins, which are ethylene polymers prepared usingsingle-site or metallocene catalysts. Therein, at least one comonomercan be polymerized with ethylene to make a copolymer, terpolymer orhigher order polymer. Also applicable are amorphous polyolefins oramorphous polyalphaolefins (APAO) which are homopolymers, copolymers orterpolymers of C2 to C8 alphaolefins.

[0069] The resin has typically a Mw below 5,000 and a Tg usually aboveroom temperature, typical concentrations of the resin in a hot melt arein the range of 30-60%. The plasticizer has a low Mw of typically lessthan 1,000 and a Tg below room temperature, a typical concentration is0-15%.

[0070] Preferably the adhesive is present in the forms of fibresthroughout the core, i.e., the adhesive is fiberized. Preferably, thefibres will have an average thickness of 1-50 micrometer and an averagelength of 5 mm to 50 cm.

[0071] To improve the adhesion of the thermoplastic material 120 to thesubstrate layer 100 or to any other layer, in particular any othernon-woven layer, such layers may be pre-treated with an auxiliaryadhesive.

[0072] Preferably, the adhesive will meet at least one, and morepreferably several or all of the following parameters:

[0073] A preferred adhesive will have a storage modulus G′ measured at20° C. of at least 30,000 Pa and less than 300,000 Pa preferably lessthan 200,000 Pa, more preferably less than 100,000 Pa. The storagemodulus G′ at 20° C. is a measure for the permanent “tackiness” orpermanent adhesion of the thermoplastic material used. Good adhesionwill ensure a good and permanent contact between the thermoplasticmaterial and for example the substrate layer 100. In a further aspect,the storage modulus G′ measured at 60° C. should be less than 300,000 Paand more than 18,000 Pa, preferably more than 24,000 Pa, most preferablymore than 30,000. The storage modulus measured at 60° C. is a measurefor the form stability of the thermoplastic material at elevated ambienttemperatures. This value is particularly important if the absorbentproduct is used in a hot climate where the thermoplastic compositionwould lose its integrity if the storage modulus G′ at 60° C. is notsufficiently high.

[0074] In a further aspect, the loss angle tan Delta of the adhesive at60° C. should be below the value of 1, preferably below the value of0.5. The loss angle tan Delta at 60° C. is correlated with the liquidcharacter of an adhesive at elevated ambient temperatures. The lower tanDelta, the more an adhesive behaves like a solid rather than a liquid,i.e., the lower its tendency to flow or to migrate and the lower thetendency of an adhesive superstructure as described herein todeteriorate or even to collapse over time. This value is henceparticularly important if the absorbent article is used in a hotclimate.

[0075] In a further aspect, the preferred adhesive should have a glasstransition temperature T_(g) of less than 25° C., preferably less than22° C., more preferably less than 18° C., and most preferably less than15° C. A low glass transition temperature T_(g) is beneficial for goodadhesion. In a further aspect a low glass transition temperature Tgensures that the adhesive thermoplastic material does not become tobrittle.

[0076] In yet a further aspect, a preferred adhesive will have asufficiently high cross-over temperature T_(x). A sufficiently highcross-over temperature T_(x) has been found beneficial for hightemperature stability of the thermoplastic layer and hence it ensuresgood performance of the absorbent product and in particular good wetimmobilization even under conditions of hot climates and hightemperatures. Therefore, T_(x) should preferably be above 80° C., morepreferably above 85° C., and most preferably above 90° C.

[0077] In a further important aspect, preferred adhesives in accordancewith the present invention will have a sufficient cohesive strengthparameter γ. The cohesive strength parameter γ is measured using therheological creep test as described hereinafter. A sufficiently lowcohesive strength parameter γ is representative of elastic adhesivewhich, for example, can be stretched without tearing. If a stress ofτ=1000 Pa is applied, the cohesive strength parameter γ is preferablyless than 100%, more preferably less than 90%, and most preferably lessthan 75%. For a stress of τ=125,000 Pa, the cohesive strength parameterγ is preferably less than 1200%, more preferably less than 1000%, andmost preferably less than 800%.

[0078] A highly preferred adhesive useful as a thermoplastic material120 as described herein will meet most or all of the above parameters.Specific care must be taken to ensure that the adhesive provides goodcohesion and good adhesion at the same time.

[0079] The process for producing preferred absorbent cores 28 inaccordance with the present invention comprises the following steps:

[0080] The absorbent core 28 is laid down onto a laydown drum, whichpresents an uneven surface. In a first process step the substrate layer100 is laid on to the uneven surface. Due to gravity, or preferably byusing a vacuum means, the substrate layer material will follow thecontours of the uneven surface and thereby the substrate layer materialwill assume a mountain and valley shape. Onto this substrate layer 100absorbent polymeric material is disposed by means known in the art. Theabsorbent polymer material will accumulate in the valleys presented bythe substrate layer 100. In a further process step a hot melt adhesiveis placed onto the absorbent polymer material.

[0081] While any adhesive application means known in the art can be usedto place the hot melt adhesive on to the absorbent polymer material, thehot melt adhesive is preferably applied by a nozzle system. Preferably,a nozzle system is utilised, which can provide a relatively thin butwide curtain of adhesive. This curtain of adhesive is than placed ontothe substrate layer 100 and the absorbent polymer material. As themountain tops of the substrate layer 100 are less covered by absorbentpolymer material the adhesive will make contact with these areas of thesubstrate layer.

[0082] In an optional further process step a cover layer 130 is placedupon the substrate layer 100, the absorbent polymer material and the hotmelt adhesive layer. The cover layer 130 will be in adhesive contactwith the substrate layer 100 in the areas of junction 140. In theseareas of junction 140 the adhesive is in direct contact with thesubstrate layer 100. The cover layer 130 will typically not be inadhesive contact with the substrate layer 100 where the valleys of thesubstrate layer 100 are filled with absorbent polymer material.

[0083] Alternatively the cover layer 130 can be laid down onto a drumwith an uneven surface and the substrate layer 100 can be added in aconsecutive process step. The embodiment shown in FIG. 4 could beproduced by such a process.

[0084] In one alternative embodiment, the cover layer 130 and thesubstrate layer 100 are provided from a unitary sheet of material. Theplacing of the cover layer 130 onto the substrate layer 100 will theninvolve the folding of the unitary piece of material.

[0085] Hence, the uneven surface of the lay-down system, whichpreferably is a lay-down drum, typically determines the distribution ofabsorbent polymeric material throughout the storage layer 60 andlikewise determines the pattern of areas of junction 140. Alternatively,the distribution of absorbent polymeric material may be influenced byvacuum means.

[0086] Preferably the distribution of absorbent polymeric material isprofiled and most preferably profiled in the longitudinal direction.Hence, along the longitudinal axis of the absorbent core, which isnormally coincident with the longitudinal axis of the absorbent article,for example of the diaper, the basis weight of the absorbent polymermaterial will change. Preferably the basis weight of absorbent polymermaterial in at least one freely selected first square measuring 1 cm×1cm is at least 10%, or 20%, or 30%, 40% or 50% higher than the basisweight of absorbent polymer material in at least one freely selectedsecond square measuring 1 cm×1 cm. Preferably the criterion is met ifthe first and the second square are centred about the longitudinal axis.

[0087] Optionally, the absorbent core can also comprise an absorbentfibrous material, for example cellulose fibres. This fibrous materialcan be pre-mixed with the absorbent polymeric material and be laid downin one process step or it can alternatively be laid-down in separateprocess steps.

[0088] It has been found beneficial to use a particulate absorbentpolymer material for absorbent cores made in the present invention.Without wishing to be bound by theory it is believed that such material,even in the swollen state, i.e., when liquid has been absorbed, does notsubstantially obstruct the liquid flow throughout the material,especially when the permeability as expressed by the saline flowconductivity of the absorbent polymer material is greater than 10, 20,30 or 40 SFC- units, where 1 SFC unit is 1×10⁻⁷ (cm³×s) /g. Saline flowconductivity is a parameter well recognised in the art and is to bemeasured in accordance with the test disclosed in U.S. Pat. No.5,599,335.

[0089] As to achieve a sufficient absorbent capacity in a preferredabsorbent article according to the present invention and especially ifthe absorbent article is a diaper or an adult incontinence product,superabsorbent polymer material will be present with a basis weight ofmore than 50, 100, 200, 300, 400, 500, 600, 700, 800 or 900 g/m².

[0090] Preferred articles according to the present invention achieve arelatively narrow crotch width, which increases the wearing comfort. Apreferred article according to the present invention achieves a crotchwidth of less than 100 mm, 90 mm, 80 mm, 70 mm, 60 mm or even less than50 mm. Hence, preferably an absorbent core according to the presentinvention has a crotch width as measured along a transversal line whichis positioned at equal distance to the front edge and the rear edge ofthe core which is of less than 100 mm, 90 mm, 80 mm, 70 mm, 60 mm oreven less than 50 mm. It has been found that for most absorbent articlesthe liquid discharge occurs predominately in the front half. The fronthalf of the absorbent core should therefore comprise most of theabsorbent capacity of the core. Preferably the front half of saidabsorbent core comprises more than 60% of the absorbent capacity, morepreferably more than 65%, 70%, 75%, 80%, 85%, or 90%.

[0091] All patents and patent applications (including any patents whichissue thereon) assigned to the Procter & Gamble Company referred toherein are hereby incorporated by reference to the extent that it isconsistent herewith.

[0092] Rheological Creep Test

[0093] Equipment:

[0094] AR 2000 Rheometer by TA Instruments as described below

[0095] Balance

[0096] Rheometer:

[0097] A test set up for carrying out the creep test employs the AR 2000Rheometer by TA Instruments. Other rheometers are available on themarket, which yield substantially the same test results. FIG. 7 providesa schematic representation of the rheometer (400). The rheometer iscapable of applying a shear stress to the adhesive and measuring theresulting strain (shear deformation) response at constant temperature.The adhesive is placed between a Peltier-element acting as lower, fixedplate (410) and an upper plate (420) with a radius R of 10 mm, which isconnected to the drive shaft of a motor to generate the shear stress.The gap between both plates has a height H of 1500 micron. ThePeltier-element enables to control the temperature of the material(±0.5° C.).

[0098] Sample Preparation:

[0099] Homogenize the adhesive at 150° C.-175° C. (depending on type ofadhesive) for 1 hour in a lab oven

[0100] Stir occasionally to ensure proper mixing of wrap and adhesive,but prevent formation of air bubbles

[0101] After homogenization in the oven pour the sample on siliconepaper for cooling

[0102] After the material is cooled to RT (room temperature), weighapproximately 0.6 g of adhesive for the creep test and place thematerial on the Peltier-plate

[0103] Test Execution:

[0104] Melt the adhesive at 120° C. (or higher if necessary) on thePeltier-plate

[0105] As soon as the adhesive is completely molten, lower the upperplate to a gap of 1500 micron to bring it into proper contact with theadhesive melt

[0106] Remove excessive material

[0107] Set the temperature to the measurement temperature of 35° C.

[0108] Set the conditioning time to 20 min to ensure thermal equilibriumbetween Peltier, adhesive and upper plate

[0109] Set constant measurement stress τ (e.g., 10,000 Pa resp. 125,000Pa) to be applied immediately to the adhesive at the beginning of theretardation step

[0110] Set the retardation time to 5 min

[0111] Set the stress to zero for immediate removal of stress at thebeginning of the recovery step

[0112] Set the recovery time to 5 min

[0113] After the test is completed, melt the adhesive, lift the upperplate and remove the adhesive from both Peltier and upper plate.

[0114] Set the temperature back to the measurement temperature orstand-by temperature (RT)

[0115] Result Reporting:

[0116] Report the strain in % (y value, herein referred to as cohesivestrength parameter) as a function of temperature and stress after 5 minapplication of stress (at the end of the retardation step), e.g., at 35°C. and 10,000 Pa resp. 35° C. and 125,000 PA as described herein.

[0117] Dynamical Mechanical Analysis (DMA)—Temperature Sweep

[0118] Equipment:

[0119] AR 2000 Rheometer by TA Instruments as described below

[0120] Balance

[0121] Rheometer:

[0122] A test set up for carrying out the temperature sweep comprisesthe AR 2000 Rheometer by TA Instruments as described herein. Otherrheometers are available on the market, which yield substantially thesame test results. FIG. 7 provides a schematic representation of therheometer (400). The rheometer is capable of applying a shear stress tothe adhesive and measuring the resulting strain (shear deformation)response at constant temperature.

[0123] The rheometer is capable of applying a small oscillatory stressto achieve a constant oscillatory strain within the linear viscoelasticregion of the adhesive (e.g., 0.05%). The instrument enables themeasurement of resulting Storage Modulus, Loss Modulus and the phaseshift between stress and strain (Loss Factor) in dependence oftemperature. The oscillation frequency is 1 Hz. The adhesive is placedbetween a Peltier-element acting as lower, fixed plate (410) and anupper plate (420) with a radius R of 10 mm, which is connected to thedrive shaft of a motor to generate the shear stress. The gap betweenboth plates has a height H of 1500 micron. The Peltier-element enablesto control the temperature of the material (±0.5° C.).

[0124] Sample Preparation:

[0125] Homogenize the adhesive at 150° C.-175° C. (depending on type ofadhesive) for 1 hour in a lab oven.

[0126] Stir occasionally to ensure proper mixing of wrap and adhesive,but prevent formation of air bubbles.

[0127] After homogenization in the oven pour the sample on siliconepaper for cooling.

[0128] After the material is cooled to RT, weigh approximately 0.6 g ofadhesive the temperature sweep and place the material on thePeltier-plate.

[0129] Test Execution:

[0130] Melt the adhesive at 120° C. (or higher if necessary) on thePeltier-plate

[0131] As soon as the adhesive is completely molten, lower the upperplate to a gap of 1500 micron to bring it into proper contact with theadhesive melt

[0132] Remove excessive material and set the temperature to themeasurement start temperature (e.g., 150° C., depending on thetemperature range of interest→see below)

[0133] Set the temperature to the start temperature depending on thetemperature range at which the rheological properties of the adhesiveneed to be determined (e.g., 150° C., in any case start with highesttemperature)

[0134] Set the conditioning time to 20 min to ensure thermal equilibriumbetween Peltier, adhesive and upper plate

[0135] Set the start temperature (see above)

[0136] Set the constant measurement strain (e.g., 0.05%)

[0137] Set the constant frequency (e.g., 1 Hz)

[0138] Set the cooling rate (e.g., 2° C./min)

[0139] Set the end temperature (e.g., −5° C.) depending on thetemperature range at which the rheological properties of the adhesiveneed to be determined and depending on the cooling capacity of thePeltier

[0140] Set the temperature to RT

[0141] After the test is completed, melt the adhesive, lift the upperplate and remove the adhesive from both Peltier and upper plate.

[0142] Set the temperature back to RT

[0143] Result Reporting

[0144] Report the Storage Modulus G′ in Pa and the Loss Factor tan Delta(dimensionless) at 20° C. and 60° C.

[0145] Report the glass transition temperature Tg in ° C. (inflectionpoint of G′)

[0146] Report the cross-over temperature Tx in ° C. at which G′ equalsG″ at the end of the rubber plateau towards higher temperature(beginning of terminal zone)

[0147] Determination of Surface Tension

[0148] The surface tension (unit: mN/m) is determined according to thefollowing test.

[0149] Apparatus:

[0150] Equipment: K10 tensiometer provided by Krüss GmbH, Germany orequivalent. The vessel elevation speed should be 4 mm/min. Liquidsurface height should be sensed automatically when using a plate or aring. The equipment must be able to adjust the sample positionautomatically to the correct height. Precision of test should be +/− 0.1mN/m.

[0151] Procedure:

[0152] 1. Pouring 40 ml of saline (0.9 wt % NaCl in deionized water)into a cleaned beaker.

[0153] 2. Testing the surface tension with a platinum ring or a platinumplate. The surface tension should be 71-72 mN/m at 20° C.

[0154] 3. Cleaning the beaker with deionized water and isopropanol andburning it out with a gas burner for a few seconds. Waiting untilequilibrate to room temperature is reached.

[0155] 4. Placing 10 60×60 mm pieces of test nonwoven into a cleanedbeaker. The nonwoven should have a basis weight of at least 10 gsm.

[0156] 5. Adding 40 ml of saline (0.9 wt % NaCl in deionized water).

[0157] 6. Stirring with a clean surfactant-free plastic stick for 10seconds.

[0158] 7. Letting the solution with nonwoven stand for 5 minutes.

[0159] 8. Stirring again for 10 seconds.

[0160] 9. Removing the nonwoven from the solvent with a cleansurfactant-free plastic stick.

[0161] 10. Letting the solution stand for 10 minutes.

[0162] 11. Testing surface tension with a platinum plate or platinumring.

[0163] Determination of Strike Through

[0164] The test is carried out based on Edana Method 150.3-96 (February1996) Liquid Strike Through Time. As a major modification compared tothe Edana Method, the test described below not only measures the firstgush but also several subsequent gushes.

[0165] Apparatus:

[0166] Lister Strike Through Equipment:

[0167] Funnel fitted with magnetic valve: Rate of discharge of 25 ml in3,5 (±0.25) seconds

[0168] Strike through plate: Constructed of 25 mm thick acrylic glass.The total weight of the plate must be 500 g. The electrodes should be ofnon-corrosive material. The electrodes are set in (4.0 mm×7.0 mm) crosssection grooves, cut in the base of the plate and fixed with quicksetting epoxy resin.

[0169] Base plate: A square of acrylic glass 125 mm×125 mmapproximately.

[0170] Ring stand to support the funnel

[0171] Electronic Timer measuring to 0.01 seconds

[0172] Burette with 50 ml capacity

[0173] Core filter paper Ahistrom Grade 989 or equivalent (averageStrike Through time 1.7 s +−0.3 s, dimensions: 10×10 cm)

[0174] Procedure:

[0175] 1. Carefully cutting the required number of samples, 12.5 cm×12.5cm touching the sample only at the edge of the sample.

[0176] 2. Taking 10 plies of core filter paper.

[0177] 3. Placing one sample on the set of 10 plies of filter paper onthe base plate. The sample should be positioned on the filter paper insuch a way that the side of the nonwoven, which is intended to face theuser's skin (when applied in an absorbent article) is uppermost.

[0178] 4. Placing the strike through plate on top with the center of theplate over the center of the test piece.

[0179] 5. Centering the burette and the funnel over the plate.

[0180] 6. Ensuring that the electrodes are connected to the timer.Switching on the timer and set the clock to zero.

[0181] 7. Filling the burette with saline solution (0.9 wt % NaCl indeionized water).

[0182] 8. Keeping the discharge valve of the funnel closed and run 5.0ml of liquid (=one gush) from the burette into the funnel.

[0183] 9. Opening the magnetic valve of the funnel to discharge 5.0 mlof liquid. The initial flow of liquid will complete the electricalcircuit and start the timer. It will stop when the liquid has penetratedinto the pad and fallen below the level of the electrodes in the strikethrough plate.

[0184] 10. Recording the time indicated on the electronic timer.

[0185] 11. Waiting for 60 seconds and continuing as of point 6 for thesecond, the third gush and any subsequent gush, with each gushcomprising 5 ml of liquid.

[0186] 12. Report: Time for the 1^(st), 2^(nd) and any subsequent gushin seconds.

[0187] All documents cited in the Detailed Description of the Inventionare, in relevant part, incorporated herein by reference; the citation ofany document is not to be construed as an admission that it is prior artwith respect to the present invention.

[0188] While particular embodiments of the present invention have beenillustrated and described, it would be obvious to those skilled in theart that various other changes and modifications can be made withoutdeparting from the spirit and scope of the invention. It is thereforeintended to cover the appended claims all such changed and modificationthat are within the scope of this invention.

What is claimed is:
 1. An absorbent core useful for an absorbent articlecomprising a substrate layer, said substrate layer comprising a firstsurface and a second surface, said absorbent core further comprising adiscontinuous layer of absorbent material, said absorbent materialcomprising an absorbent polymer material, said absorbent materialoptionally comprising an absorbent fibrous material and said absorbentfibrous material not representing more than about 20 weight percent ofthe total weight of the absorbent polymer material, said discontinuouslayer of absorbent material comprising a first surface and a secondsurface, said absorbent core further comprising a layer of thermoplasticmaterial, said layer of thermoplastic material comprising a firstsurface and a second surface wherein said second surface of saiddiscontinuous layer of absorbent material is in at least partial contactwith said first surface of said substrate layer and wherein portions ofsaid second surface of said layer of thermoplastic material are indirect contact with said first surface of said substrate layer andportions of said second surface of the said layer of thermoplasticmaterial are in direct contact with said first surface of saiddiscontinuous layer of absorbent material.
 2. An absorbent coreaccording to claim 1, wherein said thermoplastic material is a hot meltadhesive.
 3. An absorbent core according to claim 2, wherein saidthermoplastic material is fibrourised.
 4. An absorbent core according toclaim 1, wherein said layer of thermoplastic material comprises anet-like structure.
 5. An absorbent core according to claim 1, whereinsaid absorbent polymer material comprises an absorbent polymer particle.6. An absorbent core according to claim 1, wherein said absorbentpolymer material is present throughout the area of said absorbent corein a basis weight of at least about 100 g/m².
 7. An absorbent coreaccording to claim 1, comprising at least two substrate layers.
 8. Anabsorbent core according to claim 7, wherein at least one of saidsubstrate layers comprises a permanently hydrophilic non-woven having asurface tension of at least about 55 mN/m when being wetted with salinesolution and having a liquid strike through time of less than about 5 sfor a fifth gush of liquid.
 9. An absorbent core according to claim 1,comprising at least one substrate layer and at least one cover layer.10. An absorbent core according to claims 9, wherein at least one ofsaid substrate layers or at least one of said cover layers comprises apermanently hydrophilic non-woven having a surface tension of at leastabout 55 mN/m when being wetted with saline solution and having a liquidstrike through time of less than about 5 s for a fifth gush of liquid.11. A process for providing a storage layer for an absorbent core usefulin an absorbent article, said process comprising the steps of: providinga substrate material comprising a first surface and a second surface;depositing absorbent material onto said first surface of said substratematerial in a pattern, the pattern comprising at least one zone which issubstantially free of absorbent material, and the pattern comprising atleast one zone comprising absorbent material; depositing a thermoplasticmaterial onto said first surface of said substrate material and saidabsorbent material, such that portions of said thermoplastic materialare in direct contact with said first surface of said substrate andportions of said thermoplastic material are in direct contact with saidabsorbent material.
 12. A process according to claim 11, wherein saidabsorbent material comprises at least about 80 weight percent ofabsorbent polymer material.
 13. A process according to claim 11, whereinsaid zones substantially free of absorbent material are connected.
 14. Aprocess according to claim 11, wherein said zones comprising absorbentmaterial are connected.
 15. A process for providing an absorbent core,said process comprising a step of joining one or more storage layersmade in accordance with claim 11 to provide an absorbent core comprisingseveral storage layers.
 16. A process according to claim 15, wherein afirst and a second storage layer are joined, such that the first surfaceof the substrate material of the first storage layer faces the firstsurface of the substrate layer of the second storage layer.
 17. Astorage layer for an absorbent core useful in an absorbent articleobtainable by a process according to claim 11.